 Okay, so what we have here, we have one of the PZT valves hooked up to a system So we have an inlet of high pressure gas on one side and then we have a tube out to atmosphere Into a little beaker so we can see what's happening with the bubbles So what we actually do is it by just turning the voltage up on the actuator here You should see the gas flowing through the valve and bubbles appearing in the water and again if you turn the voltage down the bubbles stop So that's the principle of operation You can actually control very very high pressure gases by simply varying the voltage across the device And and then you get the output of gas at the other side